This invention is directed to an oxygenator for oxygenating and temperature-controlling blood in extracorporeal circulation during surgery.
Extracorporeal circulation has been a routine procedure in the operating room for several years. An important component in the extracorporeal blood circuit is the blood oxygenator. The function of the oxygenator is to transfer oxygen into the venous blood so that the oxygen reacts with the hemoglobin with the resultant absorption of the oxygen and release of carbon dioxide. A historical survey of blood oxygenators was published in the Dec., 1961 issue of Surgery. The article was entitled "Theme and Variations of Blood Oxygenators," by R. A. DeWall, et. al.
Three principle types of blood oxygenators are known. In the membrane oxygenator, a semi-permeable membrane separates the blood from the oxygen, and gas exchange takes place by diffusion through the membrane. One type of membrane oxygenator is described in U.S. Pat. No. 3,413,095.
In the film oxygenator, a thin film of blood is exposed to an oxygen atmosphere. One type of film oxygenator is described in the Dec. 15, 1956 issue of The Lancet, page 1246, in an article entitled "Design of An Artificial Lung Using Polyvinyl Formal Sponge."
The bubble oxygenator introduces bubbles of oxygen directly into the blood. In the bubble oxygenator described in U.S. Pat. No. 3,578,411, the bubble chamber has a continuous convoluted path to promote the intermixing of the blood and the oxygen. U.S. Pat. No. 3,807,958 describes a bubble oxygenator which employs a plurality of vertical tubes through which the blood and oxygen mixture rises. U.S. Pat. No. 3,898,045 describes a bubble oxygenator having a lattice chamber tightly packed with spherical beads which are asserted to improve gas exchange. In a bubble oxygenator described in an article published in the Aug., 1957 issue of Surgery, which was entitled "Preliminary Studies On the Sponge-Oxygenator," by Adriano Bencini, et. al., a long multi-perforated needle is positioned in a cylindrical piece of polyurethane sponge. In U.S. Pat. No. 4,067,696, the rising flow of the blood and oxygen admixture passes through a three-dimensional open cell material which is asserted to aid in gas exchange on the hemoglobin.